Add signature Random.seed

Author: ksss

core/random.rbs

@@ -96,6 +96,23 @@ class Random < RBS::Unnamed::Random_Base
                | (Float | ::Range[Float] max) -> Float
                | [T < Numeric] (::Range[T]) -> T
 
+  # <!--
+  #   rdoc-file=random.c
+  #   - Random.seed -> integer
+  # -->
+  # Returns the seed value used to initialize the Ruby system PRNG. This may be
+  # used to initialize another generator with the same state at a later time,
+  # causing it to produce the same sequence of numbers.
+  #
+  #     Random.seed      #=> 1234
+  #     prng1 = Random.new(Random.seed)
+  #     prng1.seed       #=> 1234
+  #     prng1.rand(100)  #=> 47
+  #     Random.seed      #=> 1234
+  #     Random.rand(100) #=> 47
+  #
+  def self.seed: () -> ::Integer
+
   # <!--
   #   rdoc-file=random.c
   #   - srand(number = Random.new_seed) -> old_seed

test/stdlib/Random_test.rb

@@ -29,6 +29,11 @@ def test_bytes
                       Random, :bytes, 0
   end
 
+  def test_seed
+    assert_send_type "() -> ::Integer",
+                     Random, :seed
+  end
+
   def test_new_seed
     assert_send_type  "() -> ::Integer",
                       Random, :new_seed